1. Field of the Invention
The present invention relates to a slide rail for sliding a seat.
2. Description of the Related Art
Conventionally, a driving unit for moving a seat 801 between the outside and inside of a cabin as shown in FIG. 5 has been known (for example, see Japanese Patent Laid-Open No. 2001-001811).
This driving unit is provided with a slide mechanism 811 on a rotation mechanism, and is configured so as to be capable of moving the seat 801 to the outside of the cabin after turning the seat 801 to the door side.
The slide mechanism 811 comprises a pair of inner rails 821, 821 fixed to the rotation mechanism, a pair of center rails 822, 822 provided on the outside of both the inner rails 821, 821, and a pair of outer rails 823, 823 provided on the outside of the center rails 822, 822. The seat 801 is fixed to an outer bracket 824 that is provided on the outer rails 823, 823 in a bridge-like form.
As shown in FIG. 6, in an outside face 831 of the inner rail 821, 821, a V-groove 832 having a V shape in cross section is formed, and the V-groove 832 houses steel balls 834, . . . held by a holding element 833. As shown in FIG. 7, in an inside face 835 of the center rail 822, which faces the outside face 831 of the inner rail 821, 821, a V-groove 832 is formed. Between the V-grooves 832, 832 in both the rails 821 and 822, the steel balls 834 are held so as to be movable.
Also, V-grooves 832 are formed in the outside face 841 of the center rail 822 and in the inside face 842 of the outer rail 823 as well, and steel balls 834 held by a holding element 833 are held between both the V-grooves 832, 832 so as to be movable. Thereby, each of the rails 821 to 823 are configured so as to be capable of moving in the lengthwise direction and capable of sliding the seat 801 forward and backward by the operation of the driving unit, not shown.
In such a slide rail, however, though a bracket 851 is fixed to the upper faces of the inner rails 821 with screws, there is provided no construction for keeping the distance between the facing inner rails 821, 821 in the tip end portion thereof.
Therefore, as shown in FIG. 7, a load g on the seat 801 is applied to the center rail 822, a force f directed to the slantwise inside is applied to the inner rail 821 via the steel balls 834. Thereby, deflection t toward the inside is produced on the inner rail 821, so that the seat 801 supported on the outer rails 823 shifts transversely.